This invention relates to door lock deadbolt mechanisms, and particularly to a tubular door lock having an automatically actuated deadbolt upon closure of the door.
The concept of a locking safety bolt, typically called a deadbolt, actuated automatically with closure of the door, has been employed in prior teachings. In U.S. Pat. No. 1,816,134 to Wood, for example, is disclosed a mortise type lock having an automatic deadbolt mechanism. Mortise type locks employ a large amount of space, require special forming of the lock-receiving cavity in the door, and are rarely employed anymore. Tubular locks have generally replaced mortise locks in the last several decades. Wood and metal doors are made and bored to receive the standard tubular locks.
In U.S. Pat. No. 4,561,684 entitled AUTOMATIC DEADBOLT by one of the applicants herein and assigned to the assignee herein is disclosed a tubular lock assembly specially built to achieve automatic deadbolt actuation. Such a structure works effectively. However, it does require special work on each door to enable the lock assembly to be fitted into place. Performing such installation work on wood doors takes special efforts by the lock installer. Moreover, modification of steel doors to accept the lock of that application is more complicated, being effectively done at the door manufacturing stage. This requires persuasion of the door manufacturer to change its standard door construction to accommodate the special lock. Unfortunately, door manufacturers and hardware installing builders tend to be reluctant to alter standard products and techniques.